A number of methods of producing liquid hot metal directly from ore are already known. Some of these known processes are performed only in one reactor vessel, while in other methods the melt-down vessel in separate from the reduction vessel for the iron ore.
European patent application No. 0,114,040 describes a method for producing liquid hot metal and reduction gas in a melt-down gasifier by adding coal and blowing in the oxygen-containing gas in connection with a twolayer fluidized bed of coke particles and blowing in the oxygen-containing gas on several levels.
German "offenlegungsschrift" No. 30 34 539 relates to a process for directly producing liquid hot metal from lumpy iron ore which is reduced to sponge iron in the form of a loosely packed bed by means of a hot reduction gas in a direct reduction shaft furnace, and then fed in the hot state through a discharge means to a melt-down gasifier. In this vessel the sponge iron is melted down by adding coal and oxygen-containing gas, and the reduction gas is produced for the shaft furnace.
European patent application No. 0 126 391 describes an advantageous composite process with an ore reduction vessel and a melt-down vessel, in which the reaction gases escaping from the iron melt are partly afterburned in the melt-down vessel, with the resulting heat transferred to a large extent to the melt. The reaction gases are cooled off and reduced by reducing agents on the way to the ore reduction vessel.
All known methods share, although to different extents, the disadvantage that they work with a gas surplus. Even in the known two-stage methods the gas is still relatively rich in energy after the prereduction of the iron ore and is to be used as a combustion gas. Accordingly, the economy of the described processes is clearly determined by the possible utilization of their surplus gas.